Lubrication



Patented June 9, 1942 $8 Referent LUBRICA'IION Frederick Baxter Downing,

Carneys Point,

Anthony Francis Benning, Penns Grove, and Frank Willard Johnson,Pennsville, N. J., assignors to E. I. du Pont de Nemours & Company,Wilmington, Del., a corporation of Delaware No Drawing. Originalapplication February 23,

1934, Serial No. 712,610.

Divided and this application April 10, 1936, Serial No. 73,642

39 Claims.

This invention relates to lubrication and particularly to theimprovement of extreme pressure lubricating characteristics by theaddition of assisting agents.

The advantages of a high pressure lubricant become apparent when thepresent trend in design of automotive and other machine parts, and theincreased strength of metal parts, due to the use of alloy steels, isconsidered. The pressures ordinarily found in well lubricated journalbearings do not exceed 2,000 lbs/sq. in. and for conditions such as thisa film of heavy oil can be expected to remain between the rubbingsurfaces. When gears are considered, where the contact between surfacesis of very small width, the bearing pressures often reach values as highas 25,000 lbs/sq. in. Under such extreme pressure, it is unlikely thatany oil or grease can be obtained which'will be viscous enough toprevent metallic contact. The result of the lack of a lubricating filmbetween the rubbing surfaces results in scoring and scufiing of thegears.

Failure to maintain lubricant films on idle bearing surfaces is now wellrecognized as the cause of 70 to 80% of the wear occurring on cylinderwalls of automotive and other internal combustion engines. When anengine is stopped, the oil film on the vertical surfaces soon drains offand, when the machine is again started up, an appreciable time elapsesbefore the circulation provides oil for the formation of new lubricantfilms. An assistant which, when added to the motor oil, will prevent theseparation of the oil film from the metal should prevent a large part ofthe wear now occurring.

Prior to this invention various assistants have been added to oils toimprove their lubricating properties. Among such assisting materialswhich have been used are sulfur, sulfur chloride, sulfurized oil or oilcontaining naturally occurring sulfur, various heavy metal soaps andaluminum soaps, castor oil and, recently, aliphatic-and aromatichalides. While some of these assistants, such as the sulfur and theorganic halides improve the lubricating properties of the oil to a greatextent, they have not proved to be satisfactory for use for the reasonthat they are corrosive or give rise to corrosive agents by hydrolysisor oxidation. Also, this corrosive action is greatly intensified by thepresence of small amounts of water. Some of the alkyl halides arevolatile and, hence, are soon lost. Other assistants such as the alkaliand heavy metal soaps have proved to be of little value in improving thelubricating properties of the oils, l

An object of this invention is to provide materials, which, when broughtinto contact with metal bearing surf-aces, will form a lubricating filmbetween such bearing surfaces, which lubricating film will adhere to themetal surfaces and resist high pressures. A further object of thisinvention is to provide materials which, when added to lubricatingmedia, improve their properties, particularly their adhesiveness andresistance to high pressure. A still further object is to provide amethod for retarding the wearing, scumng and seizing of bearingsurfaces, adapted to operate at high bearing pressures, by contactingsuch surfaces with materials which willform adherent films onsuchbearing surfaces, which films will not break down under high bearingpressures. Other objects are to provide new compositions of matter andto advance the art. Still other objects will appear hereinafter.

These objects may be accomplished in accordance with our invention whichcomprises maintaining a film of a lubricating medium between the metalbearing surfaces and at the same time chemically acting upon suchsurfaces by means of an organic ester of a phosphorus acid. When suchesters are brought into contact with a metal bearing surface undersuitable conditions they react with the metal of such surface to form achemical compound therewith which adheres to such surface forming a.noncorrosive lubricating film which will retard the wear of the bearingsurfaces, will withstand high bearing pressures and will preventmetallic contact of the bearing surfaces under high bearing pressures;The films have exceptional lubricating properties at all pressures butare particularly valuable at high bearing pressures and at high rubbing.speeds. Such films will not be washed from the bearing surfaces bywater, oil or organic solvents such as gasoline, naphtha and the like.

In general, the neutral esters of our invention are insuflicientlyreactive at low temperatures to react with the metal. Further, they haveinsuflicient body to provide thick film lubrication until thetemperatures and pressures become sufiiciently high to partiallydecompose them and cause them to react with the metal. Accordingly, suchneutral esters must, in general, be employed in a lubricating mediumhaving sufiicient body to provide thick film lubrication until thetemperatures and pressures become sufficiently high to decompose suchesters and cause them to react with the metal. The most satisfactorylubricating medium to be employed with our esters are the hydrocarbonlubricating oils and greases although the animal and vegetable fats andoils may also be employed.

The acid esters, on the other hand, are in general sufiiciently reactiveat ordinary room tem peratures and low bearing pressures so that theywill react with the metal to form the desired lubricating film.Accordingly, such acid esters may be employed by themselves. However, itwill usually be desired for economical reasons to employ them in aliquid carrying medium or a grease. The liquid carrying medium may beany liquid in which the ester may be dissolved, dispersed, oremulsified. It will be preferred to employ a liquid Which'isnoncorrosive to the metal in the presence of the ester. Among theliquids which have been successfully employed are vegetable oils,kerosene, naphtha, alcohols, water, lubricating oils and greases andparticularly the mineral hydrocarbon lubricating oils and greases.However, it will generally be preferred to employ even the acidphosphates in lubricating oils and greases so as to insure lubricationof the bearing surfaces until the ester has an opportunity to react andform the desired lubricating film.

Among the compounds which we have found to be particularly effective forour purpose are the aromatic and aliphatic esters of phosphoric andphosphorous acids. Among the aliphatic esters, those containing a carbonchain of at least 8 carbon atoms have proved to be the most effectiveand, of these, the mixed esters and mixtures of esters containing longchain aliphatic groups are generally preferred because of their greatersolubility in lubricating oils and greases.

When the expression long chain aliphatic (or alkyl) is employedhereinafter and in the claims, it will be understood that suchexpression means aliphatic or alkyl groups containing 8 or more carbonatoms. Also, when the term phosphorus acids is employed hereinafter andin the claims, it will be understood that this term includes the variousacids of phosphorus such as the various phosphoric, phosphorous and thiophosphorus acids. The term bearing surfaces as employed herein and inthe claims will be understood to mean surfaces which mutually carry aload and move relatively to each other.

The organic esters of the phosphorus acids of our invention may beemployed as the free esters or as their alkali salts such as the sodium,potassium, ammonium and organic amine salts. The addition of as smallamount as 0.05% to an oil will have a noticeable effect. However, forpractical use, it; will generally be found desirable to use at least0.2%. Further, the amount added to the oil or other carrier will belargely dependent upon the machinery in which it is applied and the areaof the metal surfaces with which it will be brought into contact.

The method of testing our compounds was that devised by J. O. Allmen(Oil and Gas Journal, 30, 109, 1931). This method consists of running adiameter drill rod between two halves of a split bushing which ismaintained stationary. The load on the bushing is controllable andprovision is made for measuring the torque developed by the friction ofthe lubricant film. A hydraulic system for increasing the loading on thebushing until the oil film breaks and the metal seizes is provided. Therubbing speed is about 50 feet per minute and the method of loading isgradual, one weight being added to the loading lever each ten seconds.Each weight added to the loading lever increases the pressure on'thebushing by about 125 lbs. The machine provides for beam loadings up to20 weights which corresponds to a pressure of 20,000 lbs/sq. in. on thefull projected area of the drill rod. The bearing surfaceof the bushingis cut to a diameter 0.007 inch larger than the drill rod so that.before any wear occurs, the actual bearing surface is a line. As wearoccurs, the bearing surface widens but seldom covers the bushing. Aftera test, the width of the bearing scar can be measured and an approximatevalue for the actual bearing pressure obtained. The values given in thefollowing examples represent the calculated actual bearing pressureswhich were reached in the tests without failure of the film. Thesevalues represent film strength or film resistance.

When subjected to the above test, a good grade of paraffin oil willwithstand .a pressure of only 3 to 5,000 lbs/sq. in. Whenan oilcontaining sulfur is tested by the same method, such oil will show afilm strength of about 20,000 lbs/sq. in. and will give a torque readingof over 4.0 lbs. it. at this load.

In order to more clearly illustrate our invention and the advantageousresults to be obtained thereby the following examples are given:

Example 1 Five tenths percent of dilauryl phosphate (C12H25)2HPO4 isadded to a medium viscosity (S. A. E. 30) mineral oil and the wholewarmed slightly until the ester has dissolved. When tested by the methodhereinbefore described, this oil shows a film resistance of more than55,000 lbs. per sq. in. and the friction developed is 2.0 to 2.2 lb. ft.When larger amounts of the phosphate up to 4% were added to the sameoil, the same results are obtained.

Example 2 An oil mixture was made up as in Example 1, except that 1.0%of dicetyl phosphate was employed in place of the dilauryl phosphate.The load carried on test is more than 55,000 lbs. per sq. in. and thetorque is 2.0 lb. ft.

Example 3 Five percent of tricresyl phosphate was added to a mediumviscosity (S. A. E. 30) mineral oil as in Example 1. The load carried ontest was more than 25,000 lbs. per sq. in. and the torque developed was3.5 lb. ft.

Example 4 1.0% of dicyclohexyl phosphate was added to a'medium viscositymineral oil (S. A. E. 30) The load carried was 20,000 lbs. per sq. in.and the torque developed was 1.4 lb. ft.

Ewample 5 1% of dioleyl phosphate was added to a mineral oil (S. A. E.30). The load carried was 45,000 lbs. per sq. in. and the torque was 2.0lb. ft.

Example 6 A lubricant made by dissolving 1% of dilauryl phosphate in aheavy oil (600 W), withstood a pressure of more than 52,000 lbs. per sq.in. and developed a torque at this pressure of 2.2 lb. ft.

Example 7 A lubricant was prepared as described in Example 1, exceptthat 1.0% of a mixture of diand tri-lorol phosphites was employed inplace of the dilauryl phosphate. The load carried on test was 51,000lbs. per sq. in. and the torque at this load was 2.3 lb. ft

The term lorol as employed in this and other examples and throughout thespecification and claims indicates a mixture of primary normal aliphaticalcohols of 8 and carbon atoms which are obtained by fractionation ofthe alcohols resulting from the reduction of coconut and/or palm kerneloils. These alcohols had a boiling range of 140 to 195 C. at 50 mm.Accordingly, the term lorol phosphites means the phosphorous ester ofsuch alcohols.

Example 8 One part of triphenyl phosphite ((C6H5)3 P03) mixed with 100parts of a lubricating oil withstood a bearing pressure of 48,000lbs./sq in. The friction torque was 3.2 lb. ft.

Example 9 A medium viscosity mineral oil (SAE 30) containing 1% oftrinaphthyl phosphate carried a load of 21,000 lbs. per sq. in., thetorque was 2.2 lb. ft.

Example 10 A mixture was made up of one part dilorol phosphate and 99parts of solvent naphtha. Under test, this lubricant withstood apressure of more than 45,000 lbs. per sq. in. with a friction torque of2.2 lb. ft.

Example 11 One part of dilorol phosphate was mixed with 99 parts oflorol alcohol, comprising a mixture of primary aliphatic alcoholscontaining 8 to 10 carbon, atoms. This mixture withstood a load of32,000 lbs. per sq. in. developing a torque of 2.1 lb. ft. Under thesame conditions of test, a lorol alcohol film, in the absence of thephosphate, will break with less than 4,000 lbs. pressure per sq. in.

Example 12 A mixed phosphate ester of lorol and ocenol tested alonewithstood a bearing load of 45,000 lbs. per sq. in. with a torque of 2.1lb. ft.

Ocenol comprises a mixture of primary aliphatic alcohols containing 12to 18 carbon atoms, having an iodine number of about 50 and is mostlyoleyl alcohol.

Example 13 5.0% of a naturally occurring phosphate ester, lecithin, wasadded to a lubricating oil as in Example 1. On test, this mixturewithstood a pressure of 52,000 lbs. per sq. in. and developed a torqueof 3.0 lb. ft.

Example 14 One part of dilorol phosphate was mixed with 200 parts castoroil. This mixture withstood a pressure of 60,000 lbs. per sq. in. Thefriction torque was 2.4 lb. ft.

Example 15 One part of dilorol phosphate was emulsified in 100 parts ofwater containing a small amount of caustic soda. This emulsion withstooda pres sure of 32,000 lbs. per sq. in. with a friction torque of 1.9 lb.ft.

Example 16 One part of the a-naphthylamine salt of dilorol phosphate wasmixed with 100 parts of lubricating oil. On test, this lubricantwithstood a pressure of over 55,000 lbs. per sq. in., at which load thefriction torque was 2.4 lb. ft.

' Cross Reference Example 17 One part of dilauryl dithio phosphate wascompounded with parts of lubricating oil. The pressure carried was34,000 lbs. per sq. in. The torque was 2.1 lb. ft.

Example 18 One part of mono lauryl phosphite with 99 parts of petroleumoil gave an Allmen test of over 60,000 lbs. per sq. in, at a torque of1.9 lb. ft.

The above examples merely illustrate the results obtained with a few ofthe compounds of our invention. Other compounds coming within ourinvention which we have found to be effective for our purpose are:

Di-ethyl phosphate Tri-ethyl phosphate Mixed cycloheXyl-cyclohexylphosphates Tri-ocenol phosphate Di-octyl phosphate Mixed monoanddi-lorol phosphates Mixed octyl lauryl phosphate (di-ester)Tri-methylricinoleyl phosphate Lauroxy-ethanol phosphate Themonophosphate of the diglyceride obtained by partial hydrolysis oflinseed oil Mixed phosphate esters of hydroxy stearic acidCetyl-pyridinium phosphate Di-phenyl phosphate Di-cresyl phosphateTri-nitrophenyl phosphate Tri-hexoxyphenyl phosphate Mixedtertiaryamylphenyl phosphates Mixed do'decahydro-fiphenylol propanephosphates Mixed monophosphates Mixed tetrahydro-b-naphthyl phosphatesDilorol cresyl phosphate Dibutylamine salt of mixed phosphates of lorolBenzylamine salt of mixed phosphates of lorol Amylamine salt of mixedphosphates of lorol Mixed monoand di-butyl phosphates Dilauryl trithiophosphite The monodiand tri-esters corresponding with those heretoforementioned may also be mentioned. Esters of phosphorus acids may beobtained by the treatment of a mineral or natural oil with phosphorushalides and a catalyst such as aluminum chloride. Phosphate andphosphite esters can also be obtained by the treatment of oilscontaining ethylene linkages or hydroxyl groups with phosphorus halides,oxy halides, oxides, sulfides, etc. The resultant esters will be foundto be effective for our purpose and come within the scope of ourinvention.

From the preceding description it will be apparent that the organicesters generally of the phosphorus acids are lubricants for metallicsurfaces and suitable assistants to be added to lubricating oils,greases and other liquids to form lubricating compositions for metallicsurfaces and which will be effective at extreme pressures.

The compounds of our invention, when brought into contact with metalbearing surfaces, apparently form an adherent film thereon which filmwill withstand high bearing pressures without breaking down and thuswill prevent metallic contact of the bearing surfaces. When incorporatedin an oil or grease, our compounds cause the oil and grease to adheremore firmly to the bearing surfaces. This is a particularly desirableand di-decahydro-b naphthyl and advantageous characteristic of ourcompounds, particularly adapting them for use where the bearing surfacesare vertical and an ordinary oil tends to drain therefrom, as in thecylinders of internal combustion engines. Furthermore, the film producedby our compounds remains on the bearing surfaces even after the oil orother carrying media has been drained off and continues to exert itseffect until worn off. Such film will not be removed by washing withwater, gasoline, solvent naphtha and the like.

Our compounds are non-corrosive and, in fact, some of them will inhibitcorrosion of metal by water. Our compounds are effective where therubbing speeds are high as well as where they are low as in gears.

The fact that our compounds retain their extreme pressure lubricatingcharacteristics in liquids other than oils and greases renders themparticularly adapted for use as cutting oils, particularly in wateremulsion. Our compounds may be employed in other liquids than thosementioned in the examples. For instance, they may be employed inbenzene, gasoline, diphenyl, diphenyl oxide and any other liquid whichis non-corrosive to metal and in which our compounds may be dissolved,dispersed or emulsified.

The use of cutting oils in machining operations is well known. Thecutting fluid has two functions; the first to provide a lubricant toreduce the friction between the cutting tool and the work, and thesecond to provide a means for cooling the work.

The general practice is to use either an oil or a dispersion of oil inwater. The oils used vary considerably depending on the particularoperation and may vary from a light mineral oil to a heavy mixture ofmineral and animal oils. The water suspensions are usually made up fromoils by the addition of dispersing agents of the Turkey red oil type.Recently the practice of adding sulfur or sulfur compounds has becomecommon.

Die shaping of sheet metals and drawing of sheets and wires and tubeshas also recently been improved by the use of a lubricant between thecontacting surfaces.

Cutting oils are now generally made up by compounding about 30 parts oflard oil, one to five parts of sulfur, two to ten parts of a petroleumsulfonate or Turkey red oil and about 60 parts of mineral oil. Thismixture is then used undiluted or dispersed in water which improves itscooling properties.

The lard oil, of course, breaks down under the high temperatureconditions of use resulting in the formation of disagreeably odorousmaterials. The presence of sulfur, as in motor and gear lubricants, is apossible source of corrosive material necessitating the careful washingof machined parts before use. These oils have also' given considerabletrouble from infection. 9f the workmen which is only partially eliminatdby the incorporation of a bactericide in the oil.

Wire drawing also requires an extreme pressure lubricant. Several typesare in use but essentially they are the same as the ordinary cuttingoils.

The pressures between the rubbing surfaces during all machiningoperations are obviously very high as they result in deformation of themetal. This is, therefore, another problem of extreme pressurelubrication,

Our compounds may be used in water, oil or other suitable media ascutting oil compositions with the attending elimination of the odors andcorrosiveness which are objectionable properties of most prior cuttingoils. They will be effective at very low concentrations in oil and canbe used in water directly without the use of an oil medium.

Other improvements similar to those observed on bearing lubricationshould also result from such use. Decreased friction, safety fromcorrosion, and improved quality of the work are important results oftheir use.

The compounds of our invention are in general well known and the methodsfor making them are also well known and described in the literature.These methods generally comprise the treatment of alcohols, unsaturatedaliphatic compounds or phenols with phosphorus chlorides or withphosphorous oxy chlorides or oxides. Accordingly, a detailed descriptionof the methods to be employed for making the compounds referred to inthis application is believed to be unnecessary.

This is a division of our co-pending application Serial Number 712,610,filed February 23, 1934.

While we have disclosed specific embodiments of our invention, it willbe readily apparent to those skilled in the art that many modificationsand variations may be made therein without departing from the spirit ofour invention. Accordingly, the scope of our invention is to be limitedsolely by the appended claims construed as broadly as is permissible inview of the prior art.

We claim:

1. A lubricant consisting of a hydrocarbon oil and a small quantity ofan aryl ester of phosphorus acid.

2. The method of retarding the wearing, scuffing or seizing of orreducing the friction between relatively moving bearing surfacesoperating at high pressures or high speeds such that an ordinarylubricating oil will not be retained between such surfaces, whichcomprises maintaining on such bearing surfaces a thin lubricating filmformed by the action of an ester of a phosphorous acid which film isformed by maintaining in contact with such bearing surfaces ahydrocarbon lubricating oil having incorporated therein a small amountof said ester as the primary thin film forming addition agent.

3. The method of lubricating relatively moving bearing surfaces atpressures, temperatures or speeds such that an ordinary lubricating oilwill be unable to provide effective lubrication, which comprisesmaintaining On such bearing surfaces a thin lubricating film formed bythe chemical action of an ester of a phosphorous acid on such a thinlubricating film formed by the chemical action of a hydrocarbon ester ofa phosphorous acid on such bearing surface which film is produced bymaintaining in contact with such bearing surfacesa petroleum lubricatingoil having incorporated therein a small amount of said ester as theprimary thin film forming agent. I

5. The method of lubricating relatively moving bearing surfaces atpressures, temperatures or 252. COMPOSlTlONS.

speeds such that an ordinary lubricating oil will be unable to provideeffective lubrication, which comprises maintaining on such bearingsurfaces a thin lubricating film formed by the chemical action of ahydrocarbon ester of phosphorous acid on such bearing surface which filmis produced by maintaining in contact with such bearing surfaces apetroleum lubricating oil having incorporated therein a small amount ofsaid ester as the primary thin film forming agent.

6. The method of lubricating relatively moving bearing surfaces atpressures, temperatures or speeds such that an ordinary lubricating oilwill be unable to provide effective lubrication, which comprisesmaintaining on such bearing surfaces a thin lubricating film formed bythe chemical action of an aryl ester of phosphorous acid on such bearingsurface which film is produced by maintaining in contact with suchbearing surfaces a petroleum lubricating oil having incorporated thereina small amount of said ester as the primary thin film forming agent.

7. The method of lubricating relatively moving bearing surfaces atpressures, temperatures or speeds such that an ordinary lubricating oilwill be unable to provide efiective lubrication, which comprisesmaintaining on such bearing surfaces a thin lubricating film formed bythe chemical action of triphenyl phosphite on such bearing surface whichfilm is produced by maintaining in contact with such bearing surfaces apetroleum lubricating oil having incorporated therein a small amount ofsaid triphenyl'phosphite as the primary thin film forming agent.

8. The method of lubricating relatively moving bearingsurfacesat-pressures, temperatures or speeds such that an ordinary lubricatingoil will be unable to provide effective lubrication, which comprisesmaintaining on such bearing surfaces 2. thin lubricating film formed bythe chemical action of an alkyl' ester of phosphorous acid on tressReference lubricating oil a tri-aryl ester of a phosphorous acidsufiicient substantially to retard corrosion.

13. A motor oil normally tending to produce corrosion of bearing metalsof the cadmiumsilver alloy type under conditions of automotive use,having added-thereto a small proportion of a tri-alkyl ester of aphosphorous acid suflicient substantially to retard corrosion.

14. A motor oil normally tending to produce corrosion of bearing metalsof the cadmiumsilver alloy type under conditions of automotive use,having added thereto a small proportion of a neutral organic ester ofphosphorous acid sufficient substantially to retard corrosion.

15. A motor oil normally tending to produce corrosion of bearing metalsof the cadmiumsilver alloy type under conditions of automotive use,having added thereto a small proportion of a tri-aryl ester ofphosphorous acid suflicient' 17. A lubricant for metallic bearingsurfaces v comprising a major proportion of a petroleum d a minorproportion of an organic ester of phosphorous acid.

'18. A lubricant for metallic bearing surfaces comprising a majorproportion of a petroleum lubricating oil and a minor proportion of anarosuch bearing surface which film is produced by maintaining in contactwith such bearing surfaces a petroleum lubricating oil havingincorporated therein a small amount of said ester as the primary thinfilm forming agent.

9. The method of lubricating relatively moving bearing surfaces atpressures, temperatures or speeds such that an ordinary lubricating oilwill be unable to provide efiective lubrication, which comprisesmaintaining on such bearing surfaces a thin lubricating film formed bythe chemical action of a lorol phosphite on such bearing surface whichfilm is produced by maintaining in contact with such bearing surfaces apetroleum lubricating oil having incorporated therein a small amount ofsaid lorol phcsphite as the primary thin film forming agent.

10. A motor oil normally tending to produce corrosion of bearing metalsof the cadmiumsilver alloy type under conditions of automotive use,having added thereto a small proportion, not more than two percent, oftriphenyl-phosphite suflicient substantially to retard corrosion.

11. A motor oil normally tending to produce corrosion of bearing metalsof the cadmiummatic ester of a phosphorous acid.

19. A lubricant for metallic bearing surfaces comprising a majorproportion-of a petroleumlubricating oil and aminor proportion of anaromatic ester of a phosphorous acid in which each aromatic groupcontains only one benzene ring.

20. A lubricant for metallic bearing surfaces comprising a majorproportion of a petroleum lubricating oil and a minor proportion of analiphatic ester of a phosphorous acid.

21. A lubricant for metallic bearing surfaces comprising a majorproportion of a petroleum lubricating oil and a minorproportion of ahydrocarbon ester of a phosphorous acid.

22. A lubricant for metallic bearing surfaces comprising a majorproportion of a petroleum lubricating oil and a minor proportion of anaryl ester of a phosphorous acid.

23. A lubricant for metallic bearing surfaces comprising a majorproportion of a petroleum lubricating oil and a minor proportion of analkyl ester of a phosphorous acid.

24. A lubricant for metallic bearing surfaces comprising a majorproportion of a petroleum lubricating oil and a minor proportion of atriaryl ester of a phosphorous acid.

25. A lubricant for metallic bearing surfaces comprising a majorproportion of a petroleum lubricating oil and a minor proportion of anorganic ester of phosphorous acid.

29. A lubricant for metallic bearing surfaces comprising a majorproportion of a petroleum lubricating oil and a minor proportion of aneutral organic ester of phosphorous acid.

30. A lubricant for metallic bearing surfaces comprising a majorproportion of a petroleum lubricating oil and a minor proportion of atrihydrocarbon ester of phosphorous acid.

31. A lubricant for metallic bearing surfaces comprising a majorproportion of a petroleum lubricating oil and a minor proportion of atriaromatic ester of phosphorous acid.

32. A lubricant for metallic bearing surfaces comprising a majorproportion of a petroleum lubricating oil and a minor proportion of atri-aromatic ester of phosphorous acid in which each aromatic groupcontains only one benzene ring.

33. A lubricant for metallic bearing surfaces comprising a majorproportion of apetroleum lubricating oil and a minor proportion of atriaryl ester of phosphorous acid in which each aryl group contains onlyone benzene ring.

34. A lubricant for metallic bearing surfaces comprising a majorproportion of a petroleum lubricating oil and a minor proportion of atrialiphatic ester of phosphorous acid.

35. A lubricant for metallic bearing surfaces comprising a majorproportion of a petroleum lubricating oil and a minor proportion of atrilong chain aliphatic ester of phosphorous acid.

36. A lubricant for metallic bearing surfaces comprising a majorproportion of a petroleum lubricating oil and a minor proportion of atrilong chain alkyl ester of phosphorous acid.

3'7. A lubricant for metallic bearing surfaces comprising a majorproportion of a petroleum lubricating oil and a minor proportion oftri-lorol phosphite.

38. A lubricant for metallic bearing surfaces consisting of a majorproportion of a mineral lubricating oil and a minor amount of analiphatic ester of phosphorous acid.

39. A lubricant for metallic bearing surfaces comprising a majorproportion of a petroleum lubricating oil and a minor proportion ofdi-lorol phosphite.

FREDERICK BAXTER DOWN'ING. ANTHONY FRANCIS BENNING. FRANK WILLARDJOHNSON.

